In a motor generator composed of a stator and a rotor, the stator consists of a stator core having a plurality of slots formed thereto, and coils wound around comb teeth (hereinafter also referred to simply as “teeth”) formed between the slots. On the other hand, the rotor consists of a rotor core, magnets bearing magnetic force, and a shaft working as an axis of rotation.
When power is provided to the coil in the above-described structure, a magnetic field is generated. Based on the generated magnetic field, magnetic flux flows form between the rotor and the stator, thereby providing a rotary force to the rotor. In an automobile in which the motor generator is installed as a power source, for example, the wheels are driven by this rotary force.
Regarding a stator, a great number of stator structures designed to improve an area ratio of a cross-sectional area of a slot to a cross-sectional area occupied by a coil (hereinafter also referred to as a space factor) have conventionally been disclosed (for example, refer to JP 2002-369418 A and JP 2002-544753 A).
FIG. 14 is a diagram showing a stator structure in a motor generator disclosed in JP 2002-369418 A, for example.
FIG. 14(A) shows a state in which winding 52 is wound around one pole of a multilayer core 51 constituting a part of a stator, and FIG. 14(B) shows a horizontal cross section view of FIG. 14(A).
The multilayer core 51 is formed by laminating a predetermined number of flat rolled magnetic steel sheets and strips, and includes spaces formed by a teeth part 53 and a yoke part 54 on both sides of the teeth part 53 work as slot parts 55 used for arranging the winding 52.
The multilayer core 51 is provided with an insulation cap 56 to cover an inner surface of the slot part 55 after a core end member 57 which will be described below is attached to the multilayer core 51. A predetermined number of turns of the winding 52 are wound around the perimeter of the insulation cap 56, thereby forming the state shown in FIG. 14(A).
Referring to FIG. 14(B), a width dimension W of the teeth part 53 is established in such a manner that both end faces are tapered so as to be gradually narrowed from an outer stator circumference toward an inner stator circumference. In this manner, the projected shapes of the slot parts 55 provided on both sides of the teeth part 53 are made rectangular or parallelogramatic.
FIG. 14(C) shows a state in which the winding 52 and the insulation cap 56 shown in (A) of the same figure are removed, and 14(D) shows a diagram showing (C) of the same figure viewed along the direction of an arrow D.
Referring to FIG. 14(C), core end members 57 having an outline shape substantially identical to a projected shape of the teeth part 53 are respectively attached to both ends of the lamination core 51 in a lamination direction. The core end members 57 are formed of a magnetic powder molded body, and the outer faces of winding pressure receiving surfaces 57a formed so as to extend in a step-wise manner from the outer stator circumference toward the inner circumference (refer to FIG. 14(D)).
In the above-described structure, when the lamination core 51 functions as a part of a motor generator, magnetic fluxes pass through the teeth part 53. Then, at an end of the teeth part 53 on an inner stator circumference side, a magnetic flux density becomes higher due to the smaller width dimension W, which may cause the magnetic fluxes to be saturated. With this in view, the core end members 57 attached to the both ends of the lamination core 51 in the steel-sheet lamination direction are caused to function as a magnetic path. However, because the core end members 57 have a different magnetic property depending on material, equivalent cross-sectional areas in the inner circumference side and the outer circumference side and a central portion along a radial direction are found, and established so as to have equal values between each other.
According to such a structure as described above, because dead space in the slot part 55 is minimized, thereby increasing the space factor of the winding 52 in the slot part 55, a compact and high-power motor generator can be realized.
However, in the conventional stator structure shown in FIG. 14, while the space factor of the winding 52 is increased, a part wound by the winding 52 formed along an axial direction (a coil end part) is formed in a shape protruding from the yoke part 54 due to the core end members 57 attached to the both axial ends of the teeth part 53 as can be seen from FIG. 14(D). Accordingly, mountability of motor generators comprising the stator is problematic.
Further, although the teeth part is three-dimensionally expanded along the axial direction by means of the core end members 57, the yoke part 54 remains a two-dimensional construction defined in circumferential and radial directions, which results in inevitable thickening of the yoke part 54 in the radial direction for keeping flux linkage that passes through the teeth part. Accordingly, the possibility of reducing body sizes has been limited.
Still further, because the axial length of the stator is increased due to the protruded coil end part in the conventional stator structure, it has been difficult to downsize the total axis length including the winding 52.
Therefore, the present invention, which is directed to overcome one or more problems set forth above, has an advantage to provide a compact and high-power motor generator having superior mountability, and an automobile equipped with the motor generator.